| At present, an important factor caused by surface water pollution is various pollutants coming from the output of the process and existing in the form of non-point sources in agricultural production. The artificial wetland has the characters of less investment, highly effective, convenient operation and maintenance, high Nitrogen and Phosphorus removal rate. It has being applied to treatment agricultural effluent by many countries and areas. In China, the research for treatment agricultural effluent by artificial wetland was very less, and all were carried in laboratory. So, the study can afford important parameter and scientific basis for treatment agricultural effluent by artificial wetland in the open. These studies have great significance in both theory and produce.In this paper, use the system of channels - fields - artificial wetland to analyze agricultural water wetland environment, treatment processing indicators in the quality of observation and the features of water quality of rice fields. We explore how to control the agricultural non-point source pollution, combing with observations of wetland pilots to note the wetland on agricultural non-point source pollution's controlling mechanisms, establish the small wetlands'model of the theory or experience to control agricultural non-point source pollution. The main studying results are as follows:1. The water quality of agricultural drainage does not rich the "Surface Water Environmental Quality Standard" (GB3838-2002) category of the water body standardsâ…¤, it pollutes seriously. The main standard factors of water are Total Phosphorus, Total Nitrogen and Ammonia Nitrogen. The main factors of the agricultural non-point source pollution are using more fertilizer and sewage run off. The agricultural drainage is the main way into the water body for a large number of Nitrogen, Phosphorus and other pollutants, and the main form of agricultural non-point source pollution. The study finds out that the use of "thin, light, moisture, sun" approach in the reduction of farmland irrigation water have certain effects.2. The pollutant concentration reaches the highest in wetlands imports when fertilizing. The pollutant removal efficiency from low to highly by wetland is Nitrate Nitrogen, COD, Ammonia Nitrogen, Total Nitrogen, Turbidity and Total Phosphorus. The study finds out that the best pH is 6.6 when removing Nitrogen, with the best season of June to September. The smaller difference of pH between the import and export, the better Total Phosphorus removal steadily, with the best season in September.3. Zizania aquatica have excellent efficiency for removing Total Nitrogen and Total Phosphorus, Nelumbo nucifera cannot remove Total Nitrogen and Total Phosphorus very well, while Small flower bracket plant herb can remove Total Nitrogen very well. Based on the k-C * model, we can see that control the region of farmland of 0.8 ha required wetland drainage area of about 0.1 ha.4. Unreasonable application of fertilizers and irrigation would make water serious pollution. The using of channels - field - artificial wetland system can control the agricultural non-point source pollution effectively, reduce discharge of waste, and achieve the objective of cleaner production. Based on the establishment of channel- field -artificial wetland system,we can adopt the following control measures. The first one is reducing the use of chemical fertilizers, decreasing emissions of pollutants by the reasonable way of irrigation form headwater; the second one is using the reasonable wetland area, choosing preponderant plants for crossing planting; The third one is increasing the length of drain between the farmland and wetland appropriately, controlling the sewage discharge of stream and water quality, in order to develop effectiveness of wetland optimally.
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